Women Security Experts Are Not The Enemy: A Qualitative Study on Gender-Related Communication ChallengesEffective communication is crucial for meeting security needs, yet gender-related communication challenges faced by women security experts within software development remain underexplored. In an interview study with 25 women security experts, we investigated gender-related communication challenges hindering the adoption of security requirements, and strategies to overcome these. Key challenges included the undervaluation of women’s security expertise, communication barriers, resistance to women’s security-related suggestions, and instances of hostility. Communication challenges with stakeholders who were men disrupted team collaboration, resulting in delays, weakened security measures, and increased organizational risk. Consequently, women security experts often had to adopt strategies, such as leveraging allied men and overpreparing, to assert their security competence. We further offer insights into women’s participation in security studies. Based on our findings, we provide recommendations on how to address gender-related challenges.2025AYAsli Yardim et al.Ruhr University BochumGender & Race Issues in HCITechnology Ethics & Critical HCICHI
The TaPSI Research Framework - A Systematization of Knowledge on Tangible Privacy and Security InterfacesThis paper presents a comprehensive Systematization of Knowledge on tangible privacy and security interfaces (TaPSI). Tangible interfaces provide physical forms for digital interactions. They can offer significant benefits for privacy and security applications by making complex and abstract security concepts more intuitive, comprehensible, and engaging. Through a literature survey, we collected and analyzed 80 publications. We identified terminology used in these publications and addressed usable privacy and security domains, contributions, applied methods, implementation details, and opportunities or challenges inherent to TaPSI. Based on our findings, we define TaPSI and propose the TaPSI Research Framework, which guides future research by offering insights into when and how to conduct research on privacy and security involving TaPSI as well as a design space of TaPSI.2025SRSarah Delgado Rodriguez et al.University of the Bundeswehr MunichPrivacy by Design & User ControlPasswords & AuthenticationPrivacy Perception & Decision-MakingCHI
Bridging the Gap Between Usable Security Research and Open-Source Practice — Lessons From a Long-Term Engagement With VeraCryptVeraCrypt is a freely available open-source encryption tool popular with tech-savvy users. In a 4-year effort to improve VeraCrypt’s usability to reach less tech-savvy users, we conducted 3 user studies (N=77) and found that participants struggled to successfully encrypt their devices with VeraCrypt. We iteratively redesigned the UI and instructions and suggested significant usability improvements to the VeraCrypt community. Since 7 professional developers struggled to compile the project, we created a step-by-step compilation guide and contributed 5 pull requests for bug fixes and interface improvements. However, our efforts to translate academic findings into practical applications were unsuccessful. In this work, we explore why our usability improvements failed. Due to code complexity and a lack of transparency, the OS community was concerned our changes could undermine security. Based on our findings, we provide recommendations for researchers collaborating with open-source communities.2025FRFelix Reichmann et al.Ruhr University BochumPrivacy by Design & User ControlPrivacy Perception & Decision-MakingResearch Ethics & Open ScienceCHI
Security Knight in Shining Armor: What and Who VPN Providers Claim to Shield Consumers AgainstConsumer virtual private network (VPN) providers promise online security and privacy by tunneling user traffic through their servers. However, there is a growing disparity between the users' perceptions of achievable security and privacy and the actual limitations of such services. In a large-scale, multi-step mixed methods study, we holistically investigated the degree to which 78 consumer VPN providers support or undermine proper mental models for their products and services. We collected search queries from 300 participants - coming from five countries across four continents - to identify suitable VPN providers and, subsequently their security and privacy promises. Among VPN providers’ statements, a large share contains misleading or false information, and more than half do not mention any threat agent at all. Our results extend the current research on consumer VPNs and provide a more realistic, holistic, and accurate overview of information on VPN provider websites.2025FRFelix Reichmann et al.Ruhr University BochumPrivacy by Design & User ControlPrivacy Perception & Decision-MakingCHI
ReverSim: An Open-Source Environment for the Controlled Study of Human Aspects in Hardware Reverse EngineeringHardware Reverse Engineering (HRE) is a technique for analyzing integrated circuits. Experts employ HRE for security-critical tasks, like detecting Trojans or intellectual property violations, relying not only on their experience and customized tools but also on their cognitive abilities. In this work, we introduce ReverSim, a software environment that models key HRE subprocesses and integrates standardized cognitive tests. ReverSim enables quantitative studies with easier-to-recruit non-experts to uncover cognitive factors relevant to HRE. We empirically evaluated ReverSim in three studies. Semi-structured interviews with 14 HRE professionals confirmed its comparability to real-world HRE processes. Two online user studies with 170 novices and intermediates revealed effective differentiation of participant performance across a spectrum of difficulties, and correlations between participants’ cognitive processing speed and task performance. ReverSim is available as open-source software, providing a robust platform for controlled experiments to assess cognitive processes in HRE, potentially opening new avenues for hardware protection.2025SBSteffen Becker et al.Ruhr University Bochum; Max Planck Institute for Security and PrivacyExplainable AI (XAI)Computational Methods in HCICHI
Exploring the Impact of Intervention Methods on Developers’ Security Behavior in a Manipulated ChatGPT StudyIncreased AI use in software development raises concerns about AI-generated code security. We investigated the impact of security prompts, insecure AI suggestion warnings, and the use of password storage guidelines (OWASP, NIST) on the security behavior of software developers when presented with insecure AI assistance. In an online lab setting, we conducted a study with 76 freelance developers who completed a password storage task divided into four conditions. Three conditions included a manipulated ChatGPT-like AI assistant, suggesting an insecure MD5 implementation. We found a high level of trust in AI-generated code, even when insecure suggestions were presented. While security prompts, AI warnings, and guidelines improved security awareness, 32% of those notified about insecure AI recommendations still accepted weak implementation suggestions, mistakenly considering it secure and often expressing confidence in their choice. Based on our results, we discuss security implications and provide recommendations for future research.2025RSRaphael Serafini et al.Ruhr University BochumExplainable AI (XAI)Algorithmic Transparency & AuditabilityCHI
A Qualitative Study of Adoption Barriers and Challenges for Passwordless Authentication in German Public AdministrationsPublic administrations provide critical services and manage sensitive data for a country's citizens. Recent phishing campaigns targeting public sector employees highlight their attractiveness as targets. Deploying state-of-the-art authentication technologies, such as FIDO2, can improve overall security. We conducted a mixed-methods study in Germany to understand better the practices and challenges of deploying passwordless authentication in the public sector. First, we conducted an online survey (N=108) among German public sector employees to gain insights into their experiences and challenges. Next, we partnered with an e-government vendor and performed an in-situ experiment. We let 11 employees from the public sector experience FIDO2 under real-world conditions. Our results show that only a minority of our participants were aware of current passwordless authentication procedures. In our experiment, FIDO2-based methods left an overall positive impression. Hierarchical and heterogeneous public sector structures and the need for more technical expertise and equipment were barriers to adoption.2025JHJan-Ulrich Holtgrave et al.CISPA Helmholtz Center for Information SecurityPasswords & AuthenticationPrivacy Perception & Decision-MakingCHI
A Comparative Long-Term Study of Fallback Authentication SchemesFallback authentication, the process of re-establishing access to an account when the primary authenticator is unavailable, holds critical significance. Approaches range from secondary channels like email and SMS to personal knowledge questions (PKQs) and social authentication. A key difference to primary authentication is that the duration between enrollment and authentication can be much longer, typically months or years. However, few systems have been studied over extended timeframes, making it difficult to know how well these systems truly help users recover their accounts. We also lack meaningful comparisons of schemes as most prior work examined two mechanisms at most. We report the results of a long-term user study of the usability of fallback authentication over 18 months to provide a fair comparison of the four most commonly used fallback authentication methods. We show that users prefer email and SMS-based methods, while mechanisms based on PKQs and trustees lag regarding successful resets and convenience.2024LLLeona Lassak et al.Ruhr University BochumPasswords & AuthenticationPrivacy Perception & Decision-MakingCHI
Do You Need to Touch? Exploring Correlations between Personal Attributes and Preferences for Tangible Privacy MechanismsThis paper explores how personal attributes, such as age, gender, technological expertise, or "need for touch", correlate with people's preferences for properties of tangible privacy protection mechanisms, for example, physically covering a camera. For this, we conducted an online survey (N = 444) where we captured participants' preferences of eight established tangible privacy mechanisms well-known in daily life, their perceptions of effective privacy protection, and personal attributes. We found that the attributes that correlated most strongly with participants' perceptions of the established tangible privacy mechanisms were their "need for touch" and previous experiences with the mechanisms. We use our findings to identify desirable characteristics of tangible mechanisms to better inform future tangible, digital, and mixed privacy protections. We also show which individuals benefit most from tangibles, ultimately motivating a more individual and effective approach to privacy protection in the future.2024SRSarah Delgado Rodriguez et al.University of the Bundeswehr MunichPrivacy by Design & User ControlPrivacy Perception & Decision-MakingCHI
Self-Efficacy and Security Behavior: Results from a Systematic Review of Research MethodsAmidst growing IT security challenges, psychological underpinnings of security behaviors have received considerable interest, e.g. cybersecurity Self-Efficacy (SE), the belief in one’s own ability to enact cybersecurity-related skills. Due to diverging definitions and proposed mechanisms, research methods in this field vary considerably, potentially impeding replicable evidence and meaningful research synthesis. We report a preregistered systematic literature review investigating (a) cybersecurity SE measures, (b) SE’s proposed roles, and (c) intervention approaches. We minimized selection bias by detailed exclusion criteria, interdisciplinary search strategy, and double coding. Among 174 cybersecurity SE studies (2010-2021) from 18 databases with 55,758 subjects, we identified 173 different SE measures with considerable differences in psychometric quality and validity evidence. We found 276 variables as assumed causes/outcomes of cybersecurity SE and identified 13 intervention designs. This review demonstrates the extent of methodological and conceptual fragmentation in cybersecurity SE research. We offer recommendations to inspire our research community toward standardization.2024NBNele Borgert et al.Ruhr University Bochum, Ruhr University BochumPrivacy Perception & Decision-MakingCybersecurity Training & AwarenessCHI
Understanding Users' Interaction with Login NotificationsLogin notifications intend to inform users about sign-ins and help them protect their accounts from unauthorized access. Notifications are usually sent if a login deviates from previous ones, potentially indicating malicious activity. They contain information like the location, date, time, and device used to sign in. Users are challenged to verify whether they recognize the login (because it was them or someone they know) or to protect their account from unwanted access. In a user study, we explore users' comprehension, reactions, and expectations of login notifications. We utilize two treatments to measure users' behavior in response to notifications sent for a login they initiated or based on a malicious actor relying on statistical sign-in information. We find that users identify legitimate logins but need more support to halt malicious sign-ins. We discuss the identified problems and give recommendations for service providers to ensure usable and secure logins for everyone.2024PMPhilipp Markert et al.Ruhr University BochumPrivacy by Design & User ControlPasswords & AuthenticationCHI
I see an IC: A Mixed-Methods Approach to Study Human Problem-Solving Processes in Hardware Reverse EngineeringTrust in digital systems depends on secure hardware, often assured through Hardware Reverse Engineering (HRE). This work develops methods for investigating human problem-solving processes in HRE, an underexplored yet critical aspect. Since reverse engineers rely heavily on visual information, eye tracking holds promise for studying their cognitive processes. To gain further insights, we additionally employ verbal thought protocols during and immediately after HRE tasks: Concurrent and Retrospective Think Aloud. We evaluate the combination of eye tracking and Think Aloud with 41 participants in an HRE simulation. Eye tracking accurately identifies fixations on individual circuit elements and highlights critical components. Based on two use cases, we demonstrate that eye tracking and TA can complement each other to improve data quality. Our methodological insights can inform future studies in HRE, a specific setting of human-computer interaction, and in other problem-solving settings involving misleading or missing information.2024RWRené Walendy et al.Ruhr University Bochum, Max Planck Institute for Security and PrivacyEye Tracking & Gaze InteractionVisualization Perception & CognitionCHI
52 Weeks Later: Attitudes Towards COVID-19 Apps for Different Purposes Over TimeThe COVID-19 pandemic has prompted countries around the world to introduce smartphone apps to support disease control efforts. Their purposes range from digital contact tracing to quarantine enforcement to vaccination passports, and their effectiveness often depends on widespread adoption. While previous work has identified factors that promote or hinder adoption, it has typically examined data collected at a single point in time or focused exclusively on digital contact tracing apps. In this work, we conduct the first representative study that examines changes in people’s attitudes towards COVID-19-related smartphone apps for five different purposes over the first 1.5 years of the pandemic. In three survey rounds conducted between Summer 2020 and Summer 2021 in the United States and Germany, with approximately 1,000 participants per round and country, we investigate people’s willingness to use such apps, their perceived utility, and people’s attitudes towards them in different stages of the pandemic. Our results indicate that privacy is a consistent concern for participants, even in a public health crisis, and the collection of identity-related data significantly decreases acceptance of COVID-19 apps. Trust in authorities is essential to increase confidence in government-backed apps and foster citizens’ willingness to contribute to crisis management. There is a need for continuous communication with app users to emphasize the benefits of health crisis apps both for individuals and society, thus counteracting decreasing willingness to use them and perceived usefulness as the pandemic evolves.2023MKMarvin Kowalewski et al.COVID-19 + CSCWCSCW
A World Full of Privacy and Security (Mis)conceptions? Findings of a Representative Survey in 12 CountriesMisconceptions about digital security and privacy topics in the general public frequently lead to insecure behavior. However, little is known about the prevalence and extent of such misconceptions in a global context. In this work, we present the results of the first large-scale survey of a global population on misconceptions: We conducted an online survey with n = 12,351 participants in 12 countries on four continents. By investigating influencing factors of misconceptions around eight common security and privacy topics (including E2EE, Wi-Fi, VPN, and malware), we find the country of residence to be the strongest estimate for holding misconceptions. We also identify differences between non-Western and Western countries, demonstrating the need for region-specific research on user security knowledge, perceptions, and behavior. While we did not observe many outright misconceptions, we did identify a lack of understanding and uncertainty about several fundamental privacy and security topics.2023FHFranziska Herbert et al.Ruhr University BochumPrivacy by Design & User ControlPrivacy Perception & Decision-MakingCybersecurity Training & AwarenessCHI
Home Is Where the Smart Is: Development and Validation of the Cybersecurity Self-Efficacy in Smart Homes (CySESH) ScaleThe ubiquity of devices connected to the internet raises concerns about the security and privacy of smart homes. The effectiveness of interventions to support secure user behaviors is limited by a lack of validated instruments to measure relevant psychological constructs, such as self-efficacy - the belief that one is able to perform certain behaviors. We developed and validated the Cybersecurity Self-Efficacy in Smart Homes (CySESH) scale, a 12-item unidimensional measure of domain-specific self-efficacy beliefs, across five studies (N=1247). Three pilot studies generated and refined an item pool. We report evidence from one initial and one major, preregistered validation study for (1) excellent reliability (𝛼=0.90), (2) convergent validity with self-efficacy in information security (𝑟SEIS=0.64, p<.001), and (3) discriminant validity with outcome expectations (𝑟OE=0.26, p<.001), self-esteem (𝑟RSE=0.17, p<.001), and optimism (𝑟LOT−R=0.18, p<.001). We discuss CySESH's potential to advance future HCI research on cybersecurity, practitioner user assessments, and implications for consumer protection policy.2023NBNele Borgert et al.Ruhr University Bochum, Ruhr University BochumPrivacy by Design & User ControlSmart Home Privacy & SecurityCHI
Apps Against the Spread: Privacy Implications and User Acceptance of COVID-19-Related Smartphone Apps on Three ContinentsThe COVID-19 pandemic has fueled the development of smartphone applications to assist disease management. Many "corona apps" require widespread adoption to be effective, which has sparked public debates about the privacy, security, and societal implications of government-backed health applications. We conducted a representative online study in Germany (n = 1003), the US (n = 1003), and China (n = 1019) to investigate user acceptance of corona apps, using a vignette design based on the contextual integrity framework. We explored apps for contact tracing, symptom checks, quarantine enforcement, health certificates, and mere information. Our results provide insights into data processing practices that foster adoption and reveal significant differences between countries, with user acceptance being highest in China and lowest in the US. Chinese participants prefer the collection of personalized data, while German and US participants favor anonymity. Across countries, contact tracing is viewed more positively than quarantine enforcement, and technical malfunctions negatively impact user acceptance.2021CUChristine Utz et al.Ruhr University BochumPrivacy by Design & User ControlPrivacy Perception & Decision-MakingIoT Device PrivacyCHI
HandMorph: a Passive Exoskeleton that Miniaturizes GraspWe engineered an exoskeleton, which we call HandMorph, that approximates the experience of having a smaller grasping range. It uses mechanical links to transmit motion from the wearer’s fingers to a smaller hand with five anatomically correct fingers. The result is that HandMorph miniaturizes a wearer’s grasping range while transmitting haptic feedback. Unlike other size-illusions based on virtual reality, HandMorph achieves this in the user’s real environment, preserving the user’s physical and social contexts. As such, our device can be integrated into the user’s workflow, e.g., to allow product designers to momentarily change their grasping range into that of a child while evaluating a toy prototype. In our first user study, we found that participants perceived objects as larger when wearing HandMorph, which suggests that their size perception was successfully transformed. In our second user study, we assessed the experience of using HandMorph in designing a simple toy trumpet for children. We found that participants felt more confident in their toy design when using HandMorph to validate its ergonomics.2020JNJun Nishida et al.Shape-Changing Interfaces & Soft Robotic MaterialsHand Gesture RecognitionUIST
Pen-and-paper rituals in service interaction: Combining high-touch and high-tech in financial advisory encountersAdvisory services are ritualized encounters between an expert and an advisee. Empathetic, high-touch relationship between those two parties was identified as the key aspect of a successful advisory encounter. To facilitate the high-touch interaction, advisors established rituals which stress the unique, individual character of each client and each single encounter. Simultaneously, organizations like banks or insurances rolled out tools and technologies for use in advisory services to offer a uniform experience and consistent quality across branches and advisors. As a consequence, advisors were caught between the high-touch and high-tech aspects of an advisory service. This manuscript presents a system that accommodates for high-touch rituals and practices and combines them with high-tech collaboration. The proposed solution augments pen-and-paper practices with digital content and affords new material performances coherent with the existing rituals. The evaluation in realistic mortgage advisory services unveils the potential of mixed reality approaches for application in professional, institutional settings. The blow-by-blow analysis of the conversations reveals how an advisory service can become equally high-tech and high-touch thanks to a careful ritual-oriented system design. As a consequence, this paper presents a solution to the tension between the high-touch and high-tech tendencies in advisory services.2019MDMateusz Dolata et al.MoneyCSCW
CORA, a Prototype for a Cooperative Speech-Based On-Demand Intersection AssistantWe present the first speech-based advanced driver assistance prototype. It is based on our previously proposed on-demand communication concept for the interaction between the driver and his or her vehicle. Using this concept, drivers can flexibly activate the system via speech whenever they want to receive assistance. We could show via driver simulator studies that an instantiation of this concept as an intersection assistant, supporting the driver in turning left, was well received by drivers and preferred to an alternative, vision-based system. In this paper, we present a prototype implementation and give details on how we adapted it to the intricacy of urban traffic as well as to the shortcomings of current sensor technology in establishing an adequate environment perception. The accompanying video gives an impression of the interaction between the driver and the system when cooperatively turning left from a subordinate road into crossing traffic.2019MHMartin Heckmann et al.Head-Up Display (HUD) & Advanced Driver Assistance Systems (ADAS)Voice User Interface (VUI) DesignAutoUI
The Influence of Friends and Experts on Privacy Decision Making in IoT ScenariosAs increasingly many Internet-of-Things (IoT) devices collect personal data, users face more privacy decisions. Personal privacy assistants can provide social cues and help users make informed decisions by presenting information about how others have decided in similar cases. To better understand which social cues are relevant and whose recommendations users are more likely to follow, we presented 1000 online participants with nine IoT data collection scenarios. Some participants were told the percentage of experts or friends who allowed data collection in each scenario, while other participants were provided no social cue. At the conclusion of each scenario, participants were asked whether they would allow the described data collection. Our results indicate that when friends denied data collection, our participants were more influenced than when friends allowed data collection. On the other hand, participants were more influenced by experts when they allowed data collection.In addition, we observed that influence could get stronger or wear off over a repeated sequence of scenarios. For example, when experts and friends repeatedly allowed scenarios with clear risk or denied scenarios with clear benefits, participants were less likely to be influenced by them in subsequent scenarios.2018PNPardis Emami-Naeini et al.Privacy in Homes and GroupsCSCW